1. Field of the Invention
The invention relates to a retaining assembly including a threaded engagement between a piston rod member and a piston member which serves to retain the members together during operation as part of a hydraulic piston and cylinder unit.
2. Background of the Invention
In general, it is known in the art to provide the piston and the piston rod of a hydraulic piston and cylinder unit as separate components that are threaded together by rotational movement during assembly of the piston and cylinder unit. Such a screw-type connection typically is used in lower cost units and/or lower pressure units.
Although such screw-type connection is generally suitable for low-pressure operation, there have been cases in which vibration and repeated operation of the hydraulic piston and cylinder unit has caused the piston to become unscrewed from the piston rod. It will be appreciated that complete separation of the piston from the piston rod can have disastrous consequences. Also, even if the piston only partially unscrews from the piston rod, performance of the hydraulic piston and cylinder unit and the device operatively associated therewith may be adversely affected. There exists a need to provide a screw-type connection of the kind described which does not unscrew in operation and which is cost-effective.